Catheters are often used for the delivery and withdrawal of fluids to and from a blood vessel in a patient, respectively. The fluids may be medication that is administered to the patient, or blood that is withdrawn from the patient. The catheter may also be used for hemodialysis, in which blood is withdrawn from the patient, purified and returned simultaneously through respective lumens of the catheter, and much of the catheter remains within the patient's vasculature for an extended period of time for repeated treatments.
Typically, to insert a catheter into a blood vessel, the blood vessel is located by known methods. An aspirating needle is inserted into the vessel to confirm placement within the vessel. A guide wire is then inserted through a proximal end of the aspirating needle and into the vessel. The aspirating needle is withdrawn by sliding the needle proximally over the guide wire, leaving the guide wire within the vessel. If a catheter with a sufficiently hard wall is being used, the catheter may be slid over the guide wire, directly into the vessel.
However, for some catheters, particularly soft walled catheters, a dilator is required to dilate the vessel at the insertion point in order to accommodate the insertion of the catheter. The dilator is typically inserted into a sheath and initially used as a dilator and sheath assembly. The assembly is inserted into the vessel over the guide wire and the dilator is used to dilate the insertion opening in the vessel wall. After the insertion opening is dilated, the dilator and the guide wire are removed from the vessel by removing both the dilator and the guide wire proximally from the sheath. The sheath remains in the vessel to accommodate insertion of the catheter through the sheath and into the blood vessel.
Conventional assemblies provide one-way valves within the introducer hub for hemostasis, that is, preventing blood flow from the patient's vasculature from the incision made for eventual catheter insertion; the valve seals the passageway while permitting insertion therethrough by a guidewire and a dilator and a catheter. Commonly, proximal caps are affixed to the proximal end of the introducer hub to retain the valve therewithin.
It commonly happens that blockages occur within introducer assemblies due to clotting of blood egressing the vascular incision formed for insertion of the catheter into the vasculature. Upon such an occasion, the introducer must be removed and replaced by another, a procedure that greatly extends the time needed and complicating the procedures followed by the practitioner to implant the catheter, thereby exposing the patient to greater risk of infection due to bleeding from the incision.
It is desired to provide an introducer assembly facilitating access by the practitioner to the passageway within the introducer hub to clear a blockage that may occur within the introducer.